Today a customer with corrupted data files showed up. When we enquired a bit more he told us that he had a broken I/O controller. This is one of the worst things which can happen to you!

The reason is the following: When a I/O controller starts to die it often does not happen immediately. The controller dies slowly producing more and more corrupt data. When you just write data without checking or reading them it can take days or even weeks until you discover the problem.

But the nasty thing is, that even your backup is infected with the corrupted data.

Recently the question came up if it is faster to restore a MySQL cluster when all nodes are up or only ONE node from each node group during restore.

The answer from our gurus was: All nodes up during restore! I wanted to find out why. So I set up the following cluster and started to measure:

MySQL Cluster set up

MySQL Cluster backup